The present invention relates to hydraulic pumps, and in particular to light duty pumps. Light duty pumps are typically used in hydrostatic transmissions for turf equipment propulsion systems.
Pumps, both conventional and light duty, have numerous ports for receiving connectors of fluid lines that link with the motor, reservoir, and components. One of these ports is the case drain port which connects with the case drain line that leads to the reservoir. Typically this fluid line is inflexible and is routed to mate with the pump in a designated area. When the pump does not have a port in the designated area, an adapter and extra conduit is needed to reach this other location. This is an obstacle for the mechanic when connecting the lines.
Also, it is preferable to have the port connection located in an area that is easy to access. Typically this is the top side of the pump. Port connections located in side and bottom surfaces can be difficult to access due to the limited space available. Access is needed since the pump has to be removed from the equipment when it undergoes routine maintenance or when it needs to be replaced. It is an obstacle when the port connection is located in a difficult to reach location.
Most prior art conventional pumps use one case drain port on one surface of the pump housing. An example of such a pump is shown in prior art reference U.S. Pat. No. 3,810,715 to Week et al. Conventional pumps are typically installed in a fixed direction with its shaft directed horizontally. Other prior art conventional pumps have two case drain orifices located on the top and bottom surfaces of the pump housing. This design provides more flexibility with routing to the case drain port for pumps that have the shaft directed horizontally.
Light duty pumps are less heavy than conventional pumps and can have multiple orientations. Unlike the conventional pumps, light duty pumps can have its shaft positioned upwards and downwards. For case drain line routing purposes it is advantageous to have a port accessible in each routing. Certain prior art light duty pumps have multiple ports, but these are located in the endcap of the pump. Examples of these pumps are shown in U.S. Pat. No. 6,332,393 B1 to Trimble and U.S. Pat. No. 6,494,686 B1 to Ward. The disadvantage with these style pumps is that when the pump shaft is directed upwards, the endcap and case drain orifice is on the bottom of the pump and difficult to access.